Regulation of Guinea Pig Detrusor Smooth Muscle Excitability by 17β-Estradiol: The Role of the Large Conductance Voltage- and Ca2+-Activated K+ Channels.
Regulation of Guinea Pig Detrusor Smooth Muscle Excitability by 17β-Estradiol: The Role of the Large Conductance Voltage- and Ca2+-Activated K+ Channels.
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DOI：
10.1371/journal.pone.0141950
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Petkov GV
中科院分区：
文献类型：
--
作者：
Provence A;Hristov KL;Parajuli SP;Petkov GV
雌激素替代疗法已被认为是有益的，在缓解膀胱过度活动症的症状。然而，雌激素在膀胱平滑肌（UBSM）细胞水平的确切调控机制仍不清楚。大电导电压和Ca 2+激活的K+（BK）通道是UBSM功能的关键调节因子，被认为是雌激素的非基因组靶点。这项研究提供了一个电生理学调查的作用，UBSM BK通道作为直接目标的17β-雌二醇，在人体循环中的主要雌激素。采用膜片钳技术和穿孔全细胞膜片钳技术，结合BK通道选择性抑制剂paxilline，研究了17β-雌二醇对豚鼠UBSM细胞BK通道活性的调节机制。17β-雌二醇（100 nM）显著增加去极化诱导的全细胞稳态BK电流的幅度和新鲜分离的UBSM细胞中自发瞬时BK电流的频率。用paxilline阻断BK通道后，17β-雌二醇对全细胞BK电流的增加被消除。17β-雌二醇（100 nM）显著增加（~3倍）单个BK通道开放概率，表明17β-雌二醇-BK通道直接相互作用。17β-雌二醇（100 nM）引起UBSM细胞膜电位显著超极化，用paxilline阻断BK通道可逆转这种超极化。17β-雌二醇（100 nM）对穿孔膜片钳条件下记录的L-型电压门控Ca 2+通道电流无影响。这项研究揭示了膀胱中一种新的调节机制，即BK通道被17β-雌二醇直接激活，以降低UBSM细胞的兴奋性。
Estrogen replacement therapies have been suggested to be beneficial in alleviating symptoms of overactive bladder. However, the precise regulatory mechanisms of estrogen in urinary bladder smooth muscle (UBSM) at the cellular level remain unknown. Large conductance voltage- and Ca2+-activated K+ (BK) channels, which are key regulators of UBSM function, are suggested to be non-genomic targets of estrogens. This study provides an electrophysiological investigation into the role of UBSM BK channels as direct targets for 17β-estradiol, the principle estrogen in human circulation. Single BK channel recordings on inside-out excised membrane patches and perforated whole cell patch-clamp were applied in combination with the BK channel selective inhibitor paxilline to elucidate the mechanism of regulation of BK channel activity by 17β-estradiol in freshly-isolated guinea pig UBSM cells. 17β-Estradiol (100 nM) significantly increased the amplitude of depolarization-induced whole cell steady-state BK currents and the frequency of spontaneous transient BK currents in freshly-isolated UBSM cells. The increase in whole cell BK currents by 17β-estradiol was eliminated upon blocking BK channels with paxilline. 17β-Estradiol (100 nM) significantly increased (~3-fold) the single BK channel open probability, indicating direct 17β-estradiol-BK channel interactions. 17β-Estradiol (100 nM) caused a significant hyperpolarization of the membrane potential of UBSM cells, and this hyperpolarization was reversed by blocking the BK channels with paxilline. 17β-Estradiol (100 nM) had no effects on L-type voltage-gated Ca2+ channel currents recorded under perforated patch-clamp conditions. This study reveals a new regulatory mechanism in the urinary bladder whereby BK channels are directly activated by 17β-estradiol to reduce UBSM cell excitability.